When Michael Fields called 911 on Tuesday afternoon to report that he had found a body near his yard, he said he didn’t know how the woman had died.

Investigators didn’t believe him.

Deputies noted drag marks on the grass and leaves leading to the back yard of the home where Fields was staying. They saw blood and a partial shoe print that matched the soles of his shoes. Behind the home, they found a cinderblock with blood on it.

Then there was the matter of the bloody pajamas investigators found in his home.

By late Tuesday, the Hillsborough County Sheriff’s Office had arrested Fields, 32, on charges he had fatally bludgeoned his girlfriend, Christina Mahzamani.

He was held without bail on a charge of second-degree murder with a weapon.

Deputies said Fields called 911 at 2:20 p.m. Tuesday to report he had found Mahzamani’s body along the side of his house, 2707 St. Cloud Oaks Drive. She was dead of bludgeoning to the head, an autopsy later concluded.

Fields told detectives he was Mahzamani’s boyfriend and that she came to visit him at the house on Sunday night around 11 p.m., staying a short time before she left. He said he had no further contact with her.

Mahzamani, the mother of three children ages 3, 7 and 9, was last seen at around 10 p.m. Sunday at her home. She left her home that night but never returned.

“To all Christina’s friends, please read: Christina has been missing since about 10 p.m. Sunday,” said the post from her mother, Debbie Metcalf. “If anyone has seen her or heard from her please contact me ... (I) am very concerned.”

A more recent posting updates the case:

“It is with deep regret that we must tell all of you that Christina’s body was found yesterday afternoon in Valrico. An arrest has been made in her murder.”

At 2 p.m. Monday, a relative of Mahzamani contacted the sheriff’s office after finding her abandoned 2013 Buick Enclave blocking a driveway at 511 Briar Meadows Drive in Valrico, about a half-mile from Fields’ residence and four miles from her home at 1608 Loriana St. in Brandon. Mahzamani’s car keys and other personal items were found inside the car, deputies said.

A fund was established for the three children Wednesday and by the end of the afternoon already had shown more than $2,100 in donations.